New here. I just got a 90 f250 diesel 4x4. It sat for over a year before I resurrected it last weekend. It appears that the gauges in the cluster are failing.
Temp: When I first started using it, the temp gauge would sit at the "N" in normal when off then rise as the truck heated up. Now, 1 week later, the gauge starts above the "l" in normal when off and rises up to the red mark when heated and if I turn the fan to high in the heat/ac it will peg to high side of the gauge.
Fuel: Again, when I first started driving it a week ago, the fuel gauge appeared to work normally for both tanks. Now, after I drove it 8 hours back from Louisiana and got the rear tank low, all it reads from either tank is about 1/8-1/4 full and I know the front tank is full (had fuel running out on the ground trying to top it off).

Volts: will occasionally read around 14v, but will often dip to 12v and will randomly read steady anywhere between 12v and 14v. I have checked the alt output at the batteries and the alternator and it has always been around 14v despite what the gauge reads.

Any suggestions?? Is it common for these clusters to be wildly inaccurate? I was looking at trucks in a u-pull-it and a lot of trucks of this vintage seemed to have aftermarket gauges tacked to the dash.
Thanks,
Kevin

 

Could be a bad ground/wire harness connection for the cluster? Reason I think this is it's not just 1 guage acting goofy. Hang in there, we'll figure this out eventually, just my $0.02.
Dan

 

yeah the oil pressure gauge is an idiot light, the gauges don't even have numbers just a big NORMAL in the middle lol i have an aftermarket temp gauge in my truck because of this i would get a new cluster and if it doesn't work sell it on ebay

 

I thought about the ground thing too, I just don't know where to start looking for one under the dash that would affect the cluster. From my experience with old mustangs, the cluster gets its ground through the wiring harness plugs that plug into the back. I have 2 other clusters from similar trucks and the cluster setup looks similar to that of the mustang so I would imagine they get their ground the same way. How to troubleshoot this? That is the million dollar question

 

Dust, dirt, spillage/moisture from the dash/vents, anything can cause problems with it. I would go with removing the cluster harness, spraying both male/female connections with a good electronics spray cleaner. Then go from there. Let me know. You are not alone on here. Ask away.

 

Dust, dirt, spillage/moisture from the dash/vents, anything can cause problems with it. I would go with removing the cluster harness, spraying both male/female connections with a good electronics spray cleaner. Then go from there. Let me know. You are not alone on here. Ask away.
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Oops, double post. Sorry.

 

Cleaning the plugs/socket contacts is a great way to get started on solving your problem. I too think it is a ground problem or possibly a power problem. The ground problem is much more common, but if the wiring harness was rubbed through at some point you may be losing power to the cluster also. Once the contacts are cleaned, and the cluster is checked for operation, a good thorough inspection of under the dash is where I would start to look. Look for loose/corroded ground lugs and any bare wires showing through the insulation of the wires. It is possible that the ground problem could be under the hood also.

 

I don't know if the newer trucks have a voltage regulator for the instrument cluster, but the older Fords did (60-70s, and I am sure there are other years that did) and when it went out all the electric instruments went bonkers..

Maybe someone here can verify the facts......

Just a thought....

 

That's a great idea! I forgot all about the voltage regulator, although to be honest I'm not sure if the '90s truck had the same voltage regulators or problems with them.

 

Thanks for the suggestions. I guess I will start with the cluster plugs and clean and re-install. I was planning on replacing the dash in the future anyway (mine is cracked beyond belief) so I will have the opportunity to do a detailed wiring harness inspection then if the cleaning doesn't solve the problem.

Any tips for getting the speedo cable off of the cluster without breaking anything?

Thanks,
Kevin

 

HaHa good one! Seriously though, I've always had trouble disconnecting the speedo cable. I've either had a skin transplant removed from my hand or a black and blue hand after finally getting in disconnected. The best thing I can tell you is to squeeze the white plastic back from the connection and try to gently pull it straght out.

A related question, when did they start putting the electronic sensors for speed instead of cables in the trucks?

 

My guess would be whenever they went to the electronically controlled transmissions. I have a lot more info about mustangs, and I know they went to the AODE in 94.

 

Well, no luck with cleaning the plugs to the cluster. I went as far as completely disassembling the cluster and cleaning the contacts where the gauges attach to the wiring of the cluster. The volts and oil pressure seem to be working ok, and the volts appear to be more accurate, but the gas gauge doesn't seem to be accurate and the temp gauge is not working correctly. Whenever I turn the heater fan on high, it starts moving up immediately until it eventually goes to full hot.

Any other ideas?

 

It would be nice to be able to verify if you have a bad guage for the temp or is it possible you do have an overheating problem? Are the gas guage and temp guage on the same side? If so, you might have a problem with that section of the cluster.